1. Field of the Invention
The present invention relates to a technology of bending a small diameter metal pipe.
2. Description of the Prior Arts
Conventionally, bending of a small diameter metal pipe is carried out mainly by manual working by using jigs operated manually. However, when bending of a small diameter metal pipe is carried out manually, sufficient working accuracy is not achieved and also working efficiency is poor. Meanwhile, there also are used a bending apparatus referred to as power bender which automatically carries out bending of a specific shape and a bending apparatus referred to as NC bender which automatically carries out various bending operations. Although the power bender is comparatively inexpensive in the installation cost and resolves problems in view of working accuracy and working efficiency, there are difficulties in which only bending of a specific shape can be carried out and a change in shape is difficult to deal with. Further, although the power bender can carry out complicated working to a small diameter metal pipe in a short period of time, its structure is complicated, the installation cost is problematic and also maintenance is complicated. Further, setting operation for changing working conditions is complicated and takes time.
In order to resolve the problems in the technology of bending a small diameter metal pipe as described above, there is known a technology of bending a small diameter metal pipe capable of carrying out simple and accurate bending operation to a small diameter metal pipe to be worked. The bending technology is a method of bending a small diameter metal pipe to be bent respectively set in respectively set working directions with respect to working positions at a plurality of portions of the small diameter metal pipe to be worked set in an axis center direction thereof and an apparatus thereof is constructed by a constitution having a pipe twist unit for chucking one end side of the small diameter metal pipe to be worked, setting a predetermined working direction by rotating the small diameter metal pipe to be worked centering on the axis center and moving the small diameter metal pipe to be worked in the axis center direction and setting the metal pipe at a predetermined working position and bending means for pivoting the small diameter metal pipe to be worked by a predetermined angle while pinching the metal pipe and bending the small diameter metal pipe to be worked and is generally referred to as CNC bender.
However, in the bending operation by the conventional CNC bender, when a length of a straight line at a distal end portion of the pipe is short, there is a case in which all of the bending operation cannot be carried out in the bender. In such a case, the pipe is removed from the bending apparatus while leaving the bending operation of the distal end portion of the pipe and bending is carried out by using an exclusive bending jig or the like.
FIG. 5 exemplifies a bending method in the case in which a length of a straight line at a distal end portion of a pipe is short in bending operation by the conventional CNC bender, the CNC bender 11 is provided with a pipe twist unit 11-1 having a chuck apparatus 11-2 for grasping one end side of a small diameter metal pipe P1 to be worked for setting a predetermined working direction by rotating the small diameter metal pipe P1 to be worked which is chucked by the chuck apparatus centering on the axis center and moving the small diameter metal pipe P1 to be worked in the axis center direction and setting the metal pipe at a predetermined working position and a bending apparatus 12 having a bending roller 12-1 and a clamp jig 12-2 pivoted by a predetermined angle on a peripheral face of the bending roller via the small diameter metal pipe to be worked while pressing the small diameter metal pipe P1 to be worked onto the peripheral face of the bending roller and successively bending the small diameter metal pipe to be worked from a front end side of other end thereof toward one end subjected to the bending operation, and a reaction force receive roller 12-3. Numeral 13 designates a separate bending jig.
That is, according to the conventional bending operation, one end side in a shape of a straight pipe of the small diameter metal pipe P1 to be worked is chucked by the chuck apparatus 11-2 of the pipe twist unit 11-1 of the CNC bender 11 and under the state, the bending operation is successively carried out from the front end side of the other end of the small diameter metal pipe P1 to be worked by the bending roller 12-1 and the clamp jig 12-2 for carrying out the bending operation by being pivoted by a predetermined angle on the peripheral face via the small diameter metal pipe to be worked while pressing the small diameter metal pipe P1 to the peripheral face of the bending roller and the reaction force receive roller 12-3, when the bending operation at the CNC bender 11 is finished, in the state of leaving bending operation of the distal end portion of the pipe on the side of the chuck apparatus 11-2, the small diameter metal pipe P1 to be worked is removed from the CNC bender 11 and transferred to a successive step and the distal end portion of the pipe is bent by the separate bending jig 13 to thereby finish the bending operation.
As described above, in the case of the bending operation in which the length of the distal end portion of the pipe in the bending operation by the CNC bender is short and all of the bending operation cannot be completed by the CNC bender, there poses a problem in which the bending operation needs to carry out by removing the small diameter metal pipe to be worked from the CNC bender and setting the material again to the separate working jig or the like, that is, two of the benders are needed and by using the separate working jig, not only the working accuracy is deteriorated by causing a shift in a length dimension, a shift in a twist direction or the like from a portion of the pipe which has already been bent but also time is taken in the bending operation by using the separate working jig or the like. Further, the separate bending working jig or the like used after the bending operation by the CNC bender frequently becomes exclusive depending on the shape of the bending operation and general use formation thereof is difficult.
The invention has been carried out in view of such a conventional actual situation for proposing a method of bending a small diameter metal pipe and its apparatus capable of finishing accurately all of bending operation in a CNC bender even when a linear length of a pipe distal end portion is short.
In order to resolve the above-described problem, according to a first embodiment of the invention, there is provided a method of bending a small diameter metal pipe, wherein in a method of bending a small diameter metal pipe for chucking one end of a small diameter metal pipe to be worked, carrying out a first bending operation at a first working position on a front end side of other end of the small diameter metal pipe to be worked, successively moving the small diameter metal pipe to be worked in an axis center direction thereof, carrying out a second bending operation similar to the above-described at a second working position from other end side of the small diameter metal pipe to be worked and successively carrying out the bending operations from the front end side of the other end toward the one end, before carrying out the first bending operation, a bending operation of one step or several steps is previously carried out from a pipe distal end of the one end, a portion of the small diameter metal pipe subjected to the bending operation is chucked, under the state, the bending operation is successively carried out from the front end side of the other end toward the one end subjected to the bending operation. Further, in a case in which there is a directionality in a direction of a part relative to a bending plane thereafter such as an eye joint or the like attached to a pipe end portion, after correctly producing the directionality of the part of the eye joint or the like beforehand, the one end of the small diameter metal pipe to be worked is chucked and the first bending operation is carried out at the first working position on the front end side of the other end of the small diameter metal pipe to be worked.
Further, according to a second embodiment of the invention, there is provided an apparatus of bending a small diameter metal pipe having a first bending apparatus for carrying out a bending operation to a pipe distal end of one end of a small diameter metal pipe to be worked and a second bending apparatus for chucking a portion of the small diameter metal pipe subjected to the bending operation by the first bending apparatus and carrying out successively a bending operation from a front end side of other end thereof toward the one end subjected to the bending operation under the state, wherein at least the second bending apparatus comprises a pipe twist unit movable in an axis center direction of the small diameter metal pipe to be worked, chucking the bent portion on the one end side of the small diameter metal pipe to be worked and capable of pivoting the small diameter metal pipe to be worked by a predetermined angle centering on an axis center thereof and bending means fixed to a predetermined position forward from the pipe twist unit in the axis center direction and having a bending roller and a clamp jig. for successively carrying out the bending operation from the front side of the other end of the small diameter metal pipe to be worked toward the one end subjected to the bending operation by being pivoted by a predetermined angle on a peripheral face of the bending roller via the small diameter metal pipe to be worked while pressing the small diameter metal pipe to be worked to the peripheral face of the bending roller and a reaction force receive piece.
Further, according to a third embodiment of the invention, there is provided an apparatus of bending a small diameter metal pipe having a first bending,apparatus for carrying out a bending operation to a pipe distal end of one end of a small diameter metal pipe to be worked and a second bending apparatus for chucking a portion of the small diameter metal pipe subjected to the bending operation by the first bending apparatus and successively carrying out a bending operation from a front end side of other end thereof toward the one end subjected to the bending operation under the state, wherein at least the second bending apparatus comprises a pipe twist unit movable in an axis center direction of the small diameter metal pipe to be worked, chucking the bent portion on the one end side of the small diameter metal pipe to be worked and capable of pivoting the small diameter metal pipe to be worked by a predetermined angle centering on an axis center thereof, and bending means fixed to a predetermined position forward from the pipe twist unit in the axis center direction and having a shape roll and a bending roll for successively carrying out the bending operation from the front end side of the other end of the small diameter metal pipe to be worked toward the one end subjected to the bending operation by being pivoted on a peripheral face of the shape roller by a predetermined angle while pressing the small diameter metal pipe to be worked to the peripheral face of the shape roll and a reaction receive piece.
Further, in the case of the small diameter metal pipe to be worked having a pipe end part of an eye joint or the like having a directionality relative to a bending plane thereafter at the pipe end portion, an apparatus of producing the directionality of the pipe end part of the small diameter metal pipe to be worked having the pipe end part is provided at a prestage of the first bending apparatus.